Hopefully this won't be considered a re-post (from my other thread "Fuel Pressure (Problems?)". I recently got a P0300 DTC (random misfire) and have been banging my head around trying to fix it. The misfires only come on after the engine has been suitably warmed up. I first started experiencing the problem only while cruising. Now, if I let the car sit and idle long enough for it to warm up, or if it is already warmed completely up, it will misfire at idle. When it does misfire the idle drops to around 500 and the engine shakes and vibrates quite heavily. This will happen for a min or so and then the revs pick back up and the car will idle normally for a little before it does it again (of course by now the check engine light is on and the car is in limp mode). I've checked and replaced (where necessary) the following: ignition coil and high tension leads, spark plugs, CKP, CMP, MAF, vac leaks, FPR, purge control solenoid, EGR, PCV, fuel pressure (45 PSI), and compression (185 PSI). What I am wondering is where do I look to next? My next plan of action was going to be to check my injectors (resistance), check my TPS, and my IAC valve. I am at my wit's end so any help is appreciated. Thanks in advance!
Dtc: P0300
- Thread starter igidy
- Start date
Usually 1/3 goes in the gas, 1/3 goes in the oil, 1/3 goes into the vacuum line connected to the brake booster. It works best to put it in the gas when you're at about 1/4 of a tank and run it till the fuel light comes on. In your case I would put 1/2 in the gas and half in the vacuum line connected to the brake booster. BE CAREFUL when drawing it up the vacuum line from the brake booster,... pour it very slowly,... too much, too fast can cause problems,... liquids don't compress and major engine damage can result,... just dribble it in.
I noticed there is an STP version of Seafoam (even the same shape bottle and cap) but it doesn't even mention using it in a vacuum line (just oil and gas) I assume it's the same stuff but they don't want to take responsibility for a damaged engine,... remember ,.. pour it slowly, too much liquid in the cylinders could snap off your piston rings.
A lot of guys swear by the stuff, as do I. The only problem I've heard of was a guy who had a major backfire and blew his intake apart,... his air filter landed on the driveway,... a new MAF sensor and he was good to go.
http://www.mazdas247.com/forum/showthread.php?123809501-Seafoam-Engine-flush
http://www.seafoamsales.com/motorTuneUpTechGas.htm
http://www.mazdas247.com/forum/showthread.php?123641283-seafoam-in-the-protege
I noticed there is an STP version of Seafoam (even the same shape bottle and cap) but it doesn't even mention using it in a vacuum line (just oil and gas) I assume it's the same stuff but they don't want to take responsibility for a damaged engine,... remember ,.. pour it slowly, too much liquid in the cylinders could snap off your piston rings.
A lot of guys swear by the stuff, as do I. The only problem I've heard of was a guy who had a major backfire and blew his intake apart,... his air filter landed on the driveway,... a new MAF sensor and he was good to go.
http://www.mazdas247.com/forum/showthread.php?123809501-Seafoam-Engine-flush
http://www.seafoamsales.com/motorTuneUpTechGas.htm
http://www.mazdas247.com/forum/showthread.php?123641283-seafoam-in-the-protege
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sleepwalker
Member
- :
- 2010 Mazda CX-7 i Sport
Quick note (because I know a few people who might make this mistake after reading that otherwise excellent explanation) - He is NOT saying to pour Seafoam into your brake FLUID. DO NOT WANT.
OH GOD NO!!! You disconnect the big vacuum line that powers the brake booster (there is a little spring clamp on it) then feed the Seafoam SLOWLY into that vacuum line.
(I shall edit my original post, Thanks for clarifying that.)
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I had the same symptoms not too long ago.
Did you replace your EGR valve or just check it. There may be something stuck in the internal part of the body that is preventing it from closing/opening as designed. After replacing mine, it didn't idle poorly and got rid of the P0300 code. Upon inspecting the old EGR valve, some pieces of metal came out when I actuated the valve manually. So, you might not need to replace it but clean it out thoroughly with carb cleaner.
I have actually replaced the EGR. The problem still persists. I checked the IAT and ECT and they are both good. I do notice that at idle (750 rpm) i get alot of vibration. I can't remember if it did this before but it doesn't seem normal to me. I also was doing a test drive and a P0660 code popped up. I cleared the code and it hasn't come back yet. Could a VICS/VTCS failure cause random misfires (P0300) or even the rough (vibratory) idle.
Re: Seafoam ??
Originally Posted by igidy
I did run some seafoam through the engine today. It has helped with its overall smoothness but i am still getting a misfire. While test driving the car after seafoaming it I had a CEL pop up. I pulled two codes from it. P0300 and P0660. This is the first time I had the P0660 issue. I cleared the codes and am about to take it out again and see if the code pops up again.
During this whole diagnostic process I have noticed that those actuators on the passenger side of the intake manifold are not moving at all. This already made me concerned with the VTCS/VICS.....any thoughts? could this lead to misfire?
It may take some time for the seafoam in the gas to work it's way through the fuel system and burn off more of the carbon on your pistons. From everything I've read on seafoam there has only been the one guy that had a problem and blew up his intake with an enormous back-fire but even he swears by the stuff and uses it on everything from lawn mowers to chain saws to cars and trucks and had been using it for decades. That was his first problem and it may not have been the fault of the Seafoam.
With that being said,... If it were me, I would run that stuff through and then do it again. You could have up to 12 years worth of carbon, lacquer and gum built up through the entire system. It may take even a few treatments to clear it all out. The fact that you noticed an improvement to me suggests that you're on the right track.
Once the carbon is reduced, your compression should go down, combined with cleaned out injectors, I would think your 0300 might subside.
Engine miss-fire is a big deal for our cars because of the fragile pre-cat. If raw fuel hits it, it can melt it in minutes destroying it. However not every miss-fire puts fuel to the pre-cat, a completely blocked injector would put no gas into the cylinder but would produce a miss-fire. I was PMing Pmazda who kept on cranking his car over putting raw fuel on his pre-cat and it appears to have survived his abuse,... no code. In other words the pre-cat is a bit more durable than I was thinking and if you are not miss-firing like mad then your not dumping huge amounts of fuel on to the pre-cat all at once. I believe the pre-cat can handle the occasional random miss-fire without major concern. At least until you've cleared everything out.
As far as the stuck actuators go, I would think that anything that affects fuel or air could produce a miss-fire.
There is a thread I read about freeing up the actuator a bit like the EGR cleaning process. I will try to find the thread and post it.
http://www.mazdas247.com/forum/showthread.php?123756391-VICS-solenoid-broken-what-does-that-mean
Originally Posted by igidy
I did run some seafoam through the engine today. It has helped with its overall smoothness but i am still getting a misfire. While test driving the car after seafoaming it I had a CEL pop up. I pulled two codes from it. P0300 and P0660. This is the first time I had the P0660 issue. I cleared the codes and am about to take it out again and see if the code pops up again.
During this whole diagnostic process I have noticed that those actuators on the passenger side of the intake manifold are not moving at all. This already made me concerned with the VTCS/VICS.....any thoughts? could this lead to misfire?
It may take some time for the seafoam in the gas to work it's way through the fuel system and burn off more of the carbon on your pistons. From everything I've read on seafoam there has only been the one guy that had a problem and blew up his intake with an enormous back-fire but even he swears by the stuff and uses it on everything from lawn mowers to chain saws to cars and trucks and had been using it for decades. That was his first problem and it may not have been the fault of the Seafoam.
With that being said,... If it were me, I would run that stuff through and then do it again. You could have up to 12 years worth of carbon, lacquer and gum built up through the entire system. It may take even a few treatments to clear it all out. The fact that you noticed an improvement to me suggests that you're on the right track.
Once the carbon is reduced, your compression should go down, combined with cleaned out injectors, I would think your 0300 might subside.
Engine miss-fire is a big deal for our cars because of the fragile pre-cat. If raw fuel hits it, it can melt it in minutes destroying it. However not every miss-fire puts fuel to the pre-cat, a completely blocked injector would put no gas into the cylinder but would produce a miss-fire. I was PMing Pmazda who kept on cranking his car over putting raw fuel on his pre-cat and it appears to have survived his abuse,... no code. In other words the pre-cat is a bit more durable than I was thinking and if you are not miss-firing like mad then your not dumping huge amounts of fuel on to the pre-cat all at once. I believe the pre-cat can handle the occasional random miss-fire without major concern. At least until you've cleared everything out.
As far as the stuck actuators go, I would think that anything that affects fuel or air could produce a miss-fire.
There is a thread I read about freeing up the actuator a bit like the EGR cleaning process. I will try to find the thread and post it.
http://www.mazdas247.com/forum/showthread.php?123756391-VICS-solenoid-broken-what-does-that-mean
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it seems you had the same exact prob i did PCB, i had both codes, what i did to fix it is replace both sensors that sit above the intake manifold (locate your pcv valve, look towards the firewall and then a little to the left and you will see the only 2 sensors above the intake manifold), i swapped those out with other ones from a part out and it got rid of my p0660, now the question i have for you PCB and IGIDY is have you inspected the accordion part of your intake tube, those sections are know for cracks and only expand when the engine bay is warm/hot. i replaced mine with a full CAI and that handle my sputtering/misfire problem or your P0300...hope this helps
Sounds like good info,... From the threads I read, those two solenoid valves are $70 each so that gets pretty expensive. IGIDY say's he's gonna test the solenoids and actuators so he'll know whether or not he has to replace them. I guess it's good news that an intake leak (or I guess vacuum leak of any kind) can cause a miss-fire. That means tracking down the source of the leak should be cheap and easy.
One trick I learned to find a vacuum leak was to put some rubber tubing on the end of a propane torch, then without lighting it, you can feed the gas from the tube everywhere around the engine. When the gas gets sucked in, the RPM will increase showing where the leak is. I'm thinking maybe IGIDY's actuator might have a bad diaphragm causing a leak.
I'm thinking as well that a vacuum leak causing a miss-fire wouldn't be as bad for the pre-cat because it would be very lean and perhaps be more easily handled by the pre-cat.
One trick I learned to find a vacuum leak was to put some rubber tubing on the end of a propane torch, then without lighting it, you can feed the gas from the tube everywhere around the engine. When the gas gets sucked in, the RPM will increase showing where the leak is. I'm thinking maybe IGIDY's actuator might have a bad diaphragm causing a leak.
I'm thinking as well that a vacuum leak causing a miss-fire wouldn't be as bad for the pre-cat because it would be very lean and perhaps be more easily handled by the pre-cat.
I actually had to replace my air intake hose a year ago because it had cracked. It is still in great shape. I will check the two solenoids for the VICS/VTCS and their respective diaphragms.
Also, I want to mention that this problem is very temperature related. The engine will run fine at idle temps all day long but once I take it out and bring the temperature up due to the load of driving the engine starts misfiring. Of course, if I let the engine idle long enough for it to naturally get warm enough it will start to misfire at idle. On these recent cold days I can drive the car longer but im guessing this is probably only because it is taking longer for the engine to really get to its maximum temp.
My actuators are definitely not functioning properly. I do not notice any operation on the actuator rods at all. I can manually force them to move (at which point I don't notice the engine noticing the actuation) and they will return to their initial position but I don't see them moving even when the revs increase. Also, could fuel injector failure be temperature related with a good ECT?
Also, I want to mention that this problem is very temperature related. The engine will run fine at idle temps all day long but once I take it out and bring the temperature up due to the load of driving the engine starts misfiring. Of course, if I let the engine idle long enough for it to naturally get warm enough it will start to misfire at idle. On these recent cold days I can drive the car longer but im guessing this is probably only because it is taking longer for the engine to really get to its maximum temp.
My actuators are definitely not functioning properly. I do not notice any operation on the actuator rods at all. I can manually force them to move (at which point I don't notice the engine noticing the actuation) and they will return to their initial position but I don't see them moving even when the revs increase. Also, could fuel injector failure be temperature related with a good ECT?
I had this problem, In order to fix i took out IACV and cleaned thouroughly, Took off vacuum line cleaned them out, Took off EGR cleaned it and ended up having to replace alternator as well. The alternator was not generating enough power so it would bog car out causing a misfire. The whole process cost me about $100, including alternator rebuild kit....
I checked my VICS and VTCS actuators/solenoids today. My VICS solenoid is definitely shot. The VTCS solenoid seems to operate just fine. My VTCS actuator also operates fine and moves like it says it should in the manual. The VICS actuator on the other hand seems to be a little bit tight. The manual says it should start to move between -8 and -35 kPa. My VICS actuator starts to move at -35 or less (vacuum speak) kPa. The funny thing is, once I release the vacuum off of the actuator the rod does not move back. It stays open. In order for it to close I have to manually force the mechanism. The VTCS solenoid goes right back into position once vacuum is let off. Both of my actuators will hold a tight vacuum. I will definitely replace the VICS solenoid. Being that they cost so much I'll just leave my VTCS solenoid as is until it decides to go....
Any suggestions as far as the tight VICS actuator? Is it tight or is this normal?
I checked the resistance on the IACV and it is within spec. Should I still give it a good cleaning?
Any suggestions as far as the tight VICS actuator? Is it tight or is this normal?
I checked the resistance on the IACV and it is within spec. Should I still give it a good cleaning?
I just went out to my car to play with the actuators for reference sake. Both my actuators moved when vacuum was applied (mouth suction) and returned easily when vacuum was stopped the VTCS had a sort of dampered return (perhaps because of the one way valve ??) but the VICS snapped back very quickly and freely. When I moved the actuator arm by hand I could feel the spring resistance that would pull it off when released. I don't know where that spring tension is coming from but I suspect it's from inside the actuator with a big loose spring around the diaphragm.
One guess that I'm willing to venture is that perhaps that carbon and other crud that is in your cylinders is also spread out through your intake system and gumming up your butterfly valve mechanism. If that is the case, more seafoam may definitely help.
Perhaps some spray lube of some sort may free things up a bit or you may have a broken spring inside the actuator (if that is where the spring actually is,... it may be at the butterflies)
I'm almost sure I read a thread about some guys removeing and cleaning/lubing up their actuators. I will try to find and post that thread.
Just for general info, using Google in this format works awesome. It only gives results from only our site and takes you right to the page with the quoted reference with a preview of the post on the left AND can search the site for the entire phrase within the quotes.
Everyone should learn to use this search "VISC actuator sticking" site:mazdas247.com
Remember to use Google and don't forget the space after the second Quotation marks.
(OK that search didn't yield any results for the complete phrase but did list great substitutions. "vics actuator" yields more results but not the 40,000 that this site's search engine would give,... just a manageable 79 results)
One guess that I'm willing to venture is that perhaps that carbon and other crud that is in your cylinders is also spread out through your intake system and gumming up your butterfly valve mechanism. If that is the case, more seafoam may definitely help.
Perhaps some spray lube of some sort may free things up a bit or you may have a broken spring inside the actuator (if that is where the spring actually is,... it may be at the butterflies)
I'm almost sure I read a thread about some guys removeing and cleaning/lubing up their actuators. I will try to find and post that thread.
Just for general info, using Google in this format works awesome. It only gives results from only our site and takes you right to the page with the quoted reference with a preview of the post on the left AND can search the site for the entire phrase within the quotes.
Everyone should learn to use this search "VISC actuator sticking" site:mazdas247.com
Remember to use Google and don't forget the space after the second Quotation marks.
(OK that search didn't yield any results for the complete phrase but did list great substitutions. "vics actuator" yields more results but not the 40,000 that this site's search engine would give,... just a manageable 79 results)
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Yeah.... I figured that it should move back on its own quite easily like the VTCS actuator did. I'm not sure where the spring is either but I would suspect its on the butterfly mechanism? From my previous experience with engines and these type of butterfly valves the springs are usually not at the actuator. I may be wrong on this particular car though. Even getting to the actuator is kind of a pain I can't imagine trying to work on it.... hrmmmm.
I couldn't find the thread about cleaning it but perhaps some spray lube like PB Blaster in and around the actuator and rod connection might get things moving better??
From looking at the pictures from this thread:
http://www.mazdas247.com/forum/showthread.php?123686735-ViCS-vs-VTCS-with-PICS!
You can see how the rod would run through the whole intake mani. connecting to all four butterflies. The rod could be carboned up and restricting movement.
I just went out and looked at the actuator again and noticed that you can easily disconnect the actuator rod from the butterfly rod. There is a tiny c-clip (they call it an e-ring in the manual) on the end of the butterfly rod that you could pop off with a tiny flat head screwdriver or something. The problem with that would be losing the c-clip. Perhaps jamming the whole area with rags to catch it when it pops off and a magnet underneath it would catch it.
If you get it disconnected you could tell if the rod returns by itself when the vacuum is stopped and if there is friction on the butterfly rod. You could probably tell where the spring tension is coming from as well.
Just to make sure, because there is major confusion about the VICS and VTCS systems, I'm talking about the lower actuator with the rod coming up pointing toward the firewall.
From looking at the pictures from this thread:
http://www.mazdas247.com/forum/showthread.php?123686735-ViCS-vs-VTCS-with-PICS!
You can see how the rod would run through the whole intake mani. connecting to all four butterflies. The rod could be carboned up and restricting movement.
I just went out and looked at the actuator again and noticed that you can easily disconnect the actuator rod from the butterfly rod. There is a tiny c-clip (they call it an e-ring in the manual) on the end of the butterfly rod that you could pop off with a tiny flat head screwdriver or something. The problem with that would be losing the c-clip. Perhaps jamming the whole area with rags to catch it when it pops off and a magnet underneath it would catch it.
If you get it disconnected you could tell if the rod returns by itself when the vacuum is stopped and if there is friction on the butterfly rod. You could probably tell where the spring tension is coming from as well.
Just to make sure, because there is major confusion about the VICS and VTCS systems, I'm talking about the lower actuator with the rod coming up pointing toward the firewall.
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